The present invention relates generally to frozen confections and beverages. More particularly, the present invention relates to a process for forming an oat-based, non-dairy frozen confection and an oat-based, non-dairy beverage.
Consumers are increasingly concerned about purchasing and consuming products that the consumers view as being more healthful. For example, products possessing higher levels of complex carbohydrates and fiber, especially soluble fiber, are becoming more popular with consumers. In addition, products containing lower levels of fat and cholesterol as well as a decreased caloric content are becoming more popular with consumers. Many consumers also desire products made from all-natural components that contain no stabilizers, emulsifiers, or other exogenous additives, such as refined sugars or artificial sweeteners.
Non-dairy sweet confections are becoming popular alternatives to conventional dairy-based frozen confections. Consumers who are lactose intolerant are especially interested in purchasing products that do not contain dairy products or dairy derivatives.
One drawback of products produced for the health conscious market is that they tend to be less sweet than conventional dairy-based frozen desserts. This problem has been overcome by the addition of various sweeteners, such as sucrose, glucose syrup, and high fructose corn syrup. While these products may appeal to some segments of the health conscious market, these products are not desired by consumers who exclude refined or artificial sweeteners from their diet.
A variety of non-dairy compositions have been developed that appeal to the various segments of the health conscious market. Unfortunately, none of the products deliver all of the benefits of being lactose free, high in soluble fiber, free of exogenous additives, and sweet without the addition of refined sugars and artificial sweeteners. A product that delivers all these benefits would be acceptable as a substitute for dairy-based products even by consumers who are not interested in the health benefits of such a product.
An article by Janet Raloff (Beyond Oat Bran, Food Technology 1991 (8), at 62) describes the physiological benefits of consuming an oat-based product, which is identified by the name Oatrim. The oat-based product is formulated from either oat bran or oat flour. The article indicates that the odorless and nearly tasteless oat-based product is particularly suited as a fat replacement in low-temperature applications, such as frozen confections.
The oat-based product is described in further detail in Inglett, U.S. Pat. Nos. 4,996,063 and 5,082,673. A mixture of oats and water is gelatinized by passage through a steam injection cooker at a temperature of between 138xc2x0 C. and 143xc2x0 C. After the pH of the mixture is adjusted, alpha-amylase enzymes are added to hydrolyze the starch in the mixture. Once hydrolyzation is complete, soluble fiber is separated from the mixture. Finally, the soluble fiber is dehydrated to provide the oat-based product. Examples in the Inglett patents indicate that the oat-based product is mixed with additional components, such as milk and sugar, to formulate the frozen confection.
Mitchell et al., U.S. Pat. No. 4,744,992, discloses using a dual enzyme method, which includes liquefying and saccharifying rice, to produce a high glucose syrup. Examples in the Mitchell et al. patent indicate that when the syrup is incorporated into a frozen confection, vegetable oil in a concentration of approximately 10 percent by weight of the frozen confection as well as stabilizers are added to provide the frozen confection with a creamy texture.
Murtaugh et al., U.S. Pat. No 4,908,223, discloses an oat- or rice-based frozen confection and a method of preparing the frozen confection. Murtaugh et al. describes cooking an aqueous mixture of oats or rice. After the cooking is complete, liquefying, sweetening, and flavoring agents are added to the mixture so that the frozen confection exhibits ice cream-like characteristics.
Murtaugh et al., U.S. Pat. No. 4,908,223, discloses an oat or rice-based frozen confection and a method of preparation. Murtaugh et al. describes that refined sweeteners are added to improve the functional and organoleptic properties of the product.
Several fruit-based frozen confections have also been developed. For example, Feldpausch, U.S. Pat. No. 4,948,614, describes using bananas to produce a non-dairy confection. Blake et al., U.S. Pat. No. 4,335,155, discloses that any fruit, which can be made into a puree, is suitable for use as a base of a frozen confection. Blake, U.S. Pat. No. 4,244,981, describes using citrus juice vesicles as the primary component of a frozen confection.
The present invention includes a process for forming a non-dairy frozen confection. The non-dairy frozen confection is formed from a syrup that is frozen using conventional techniques. The syrup product is produced by liquefying and saccharifying a starch source, which is primarily oat flour or waxy barley hybrid flour. The non-dairy frozen confection exhibits ice cream-like characteristics without exogenous sweeteners, stabilizers, emulsifiers, or proteins.
The present invention includes a process for forming a non-dairy, frozen confection. The frozen confection is made from a sweet, bland, and clean tasting syrup product. The syrup product is substantially prepared from oat flour or waxy barley hybrid flour.
The frozen confection of the present invention has several advantages over prior art frozen confections. The frozen confection exhibits desirable sweetness, texture, and mouthfeel characteristics without exogenous sweeteners, stabilizers, emulsifiers, or proteins, which are commonly used in prior art non-dairy frozen confections. As used herein, the term xe2x80x9cmouthfeelxe2x80x9d refers to a creamy sensation that a person experiences in one""s mouth upon consuming ice cream. As used herein, the term xe2x80x9cexogenousxe2x80x9d refers to components that are added to prior art frozen confections to supplement or modify the characteristics of the prior art frozen confections.
Furthermore, when producing the frozen confection of the present invention, the syrup product does not require emulsification or homogenization. The prior art non-dairy frozen confections typically require emulsification and homogenization to produce characteristics that are commonly associated with dairy-based frozen confections.
The properties of the frozen confection are dictated by the particular oat or grain components selected. It has been found that using a low bran flour, which is depleted in bran while retaining soluble fiber glucans, provides a frozen confection with desired characteristics. The typical compositional analysis of low bran oat flour is similar to whole oat flour for moisture, protein, and fat, as illustrated in Table 1. However, low bran oat flour contains a lower level of bran than whole oat flour. Low bran oat flour also retains a substantial percentage of the soluble fiber that is present in whole oat flour.
While it is also possible to use oats or grains having a significant hull, bran, or husk portion to formulate the syrup, syrup formed from these materials must be separated from insoluble branny particles present in the syrup before the frozen confection is produced from the syrup. As an alternative to using the oats in the form of flour, it is also possible to practice the present invention with other forms of oats, such as rolled oats, partially milled oats, and oatmeal. These various forms of oats are collectively identified as xe2x80x9coat materialxe2x80x9d.
One particular oat flour possessing a low level of bran or hull material is patent oat flour. Patent oat flour is a fraction of the whole oat flour obtained from a mill stream early in the oat milling process. The patent oat flour contains a smaller concentration of the bran or hull material than oat flour stream occurring later or downstream in the milling process. This oat flour is referred to as patent oat flour because it has similar characteristics to patent wheat flour that is produced by a process commonly used in the production of wheat flour for bread or other baked products.
The typical compositional analysis of patent oat flour is similar to whole oat flour for moisture, protein, and fat, as illustrated in Table 1. Patent oat flour also retains a substantial percentage of the soluble fiber that is present in whole oat flour. However, patent oat flour contains less bran or insoluble fiber and more starch than whole oat flour.
The various fractions formed in the oat milling stream produce frozen products with varied characteristics. The fractions high in soluble fiber, including whole oat flour and oatmeal tend to give very smooth and somewhat xe2x80x9cdryxe2x80x9d texture to soft-serve frozen dessert, while those higher in starch content (e.g., patent oat flour) tend to provide more sweetness. It will be obvious to those skilled in the art that a desired set of finished product characteristics may be obtained by selecting an appropriate oat starting material or blend of available oat milling fractions. For example, the frozen confection may be formed from a mixture of patent oat flour and whole oat flour. Oat mill products possessing these characteristics can be obtained from various sources including Conagra, Inc (Council Bluffs, Iowa) or Grain Millers (Minneapolis, Minn.).
It has also been found that a waxy barley hybrid flour also provides desirable results when used with the present invention. The waxy barley hybrid is a hull-less barley that is preferably selected from the prowashneupana variety, which can be obtained from Conagra, Inc. (Council Bluff, Iowa). The typical compositional analysis for the prowashneupana waxy barley hybrid is set forth in Table 2.
Other starch sources can be used in conjunction with the oat flour or waxy barley hybrid flour to adjust the flavor and sweetness of the frozen confection. While other starch sources may be used in the preparation of the frozen confection, the other starch sources only represent a minor portion of oat or grain material that is used to prepare the frozen confection. The oat flour and waxy barley hybrid flour comprise a major portion of the oat or grain material that is used to prepare the frozen confection.
Examples of starch sources that are suitable for use in the present invention include flours, such as corn flour, wheat flour, rice flour, and potato flour. It is believed that the addition of other starch sources to the oat flour or waxy barley hybrid flour does not affect the functional properties of the frozen confection, such as texture and mouthfeel characteristics, associated with ice cream-like qualities.
As a preliminary step in the preparation of the frozen confection, the oat flour or waxy barley hybrid flour may be milled to a fine granulation. The term xe2x80x9cfine granulationxe2x80x9d means less than 10 percent of the oat flour or waxy barley hybrid flour was retained on a 200 U.S. mesh screen.
A base formulation is created by blending the selected starch sources. A slurry is formed by mixing the base formulation into water in an amount that is effective to provide a solids level of between 25 and 33 percent on a dry matter basis. The water is preferably potable tap water that is provided at a traditional faucet temperature of about 10xc2x0 C.
Changing the solids level allows the sweetness of the non-dairy frozen confection to be adjusted. For example, increasing the solids level causes an increase in the sweetness of the non-dairy frozen confection.
Alpha-amylase enzymes are then added to the slurry. The alpha-amylase enzymes are preferably alpha-1,4-glucan, 4-glucanohydrolase, which is derived from Bacillus subtilis. The alpha-amylase enzymes not only produce liquefaction in a random fashion over a broad range of temperatures (65xc2x0 C. to 92xc2x0 C.) but also retain its activity when used at temperatures of less than 80xc2x0 C.
The alpha-amylase enzymes are preferably food grade alpha-amylase enzymes, which can be obtained from Genencor International (Rochester, N.Y.) under the designation MULTIFECT H-39C. The MULTIFECT H-39C enzymes are added to the slurry in a concentration of between 0.0020 and 0.0080 percent by weight of the slurry and preferably in a concentration of approximately 0.0040 percent by weight of the slurry.
Converting the starch mixture into the syrup product is preferably accomplished using a three-step process. The first step, which is referred to as liquefaction, involves converting the slurry into an intermediate syrup. Liquefaction includes two elements. In the first element, microscopic starch granules in the starch mixture swell and eventually rupture. Rupturing of the microscopic starch granules causes the viscosity of the slurry to significantly increase. Once the viscosity of the slurry significantly increases, the starch is referred to as being gelatinized. Gelatinization renders the starch more susceptible to partial hydrolysis.
In the second element, the alpha-amylase enzymes cause the starch to partially hydrolyze into dextrin. In conjunction with the partial hydrolysis of the starch, the viscosity of the slurry is reduced.
The slurry is heated to a temperature of approximately 58xc2x0 C. to 60xc2x0 C. at which the viscosity of the slurry visibly increases. As an alternative to visually observing the increase in the slurry viscosity, the viscosity increase in the slurry may be determined by monitoring the amperage requirement of the mixing motor.
After the viscosity of the slurry increases, the rate at which the slurry is heated is decreased to allow the slurry to uniformly gel. The decreased heating rate also avoids scorching the slurry, which results from the rapid decrease in heat transfer caused by the increase in the viscosity of the slurry. Once the slurry reaches a target temperature of approximately 75xc2x0 C., the slurry is maintained at the target temperature for approximately 1 hour.
The hold time allows the alpha-amylase enzymes to liquify the starch as the starch gels by converting the starch into dextrin. The conversion of starch into dextrin causes the slurry to change into an intermediate syrup. As the slurry is converted into the intermediate syrup, the raw flavor of the slurry is reduced. The reduction of off-flavors in the intermediate syrup can be monitored by tasting samples of the intermediate syrup at selected intervals while the slurry is held at the target temperature.
The intermediate syrup is then hot filtered to remove portions of the slurry that have not been broken down during the liquefaction process. Conventional screens or filters having a U.S. mesh size of 30 or smaller are suitable for use with the present invention. The filtered intermediate syrup is then cooled to a saccharification temperature of between approximately 60xc2x0 C. and 65xc2x0 C.
In the second step, which is referred to as saccharification, the dextrin in the filtered intermediate syrup is converted into glucose. The conversion of dextrin into glucose causes the syrup product to exhibit a high degree of sweetness.
The dextrin is preferably converted into glucose using glucoamylase enzymes. The glucoamylase enzymes are also referred to as fungal 1,4-alpha-D-glucan glucohydrolase, which can be obtained from Genencor International (Rochester, N.Y.) under the designation SPEZYME GA 300.
The concentration of the glucoamylase enzymes is selected based upon the desired length of the saccharification time. For example, it has been found that using a glucoamylase enzyme concentration of between 0.090 and 0.130 percent by weight of the filtered intermediate syrup provides a saccharification time of between 1 and 3 hours. Alternatively, using a glucoamylase enzyme concentration of approximately 0.016 percent by weight of the filtered intermediate syrup with a saccharification time of up to 24 hours provides a syrup product with similar properties.
An advantage of using glucoamylase enzymes in the process of the present invention is that the pH of the filtered intermediate syrup does not have to be adjusted to obtain a desired enzyme activity.
At a given concentration of glucoamylase enzymes, the sweetness of the syrup product can be changed by varying the saccharification time. For example, increasing the saccharification time increases the sweetness of the syrup product. While it is possible to obtain higher sweetness levels by increasing the glucoamylase concentration with a commercially reasonable saccharification time of less than 3 hours, the higher concentration may adversely affect the flavor of the finished syrup product. Using longer saccharification times of up to 24 hours produce higher sweetness levels but saccharification times in this range may not be commercially feasible.
It has been found that the sweetness of the syrup product can be further enhanced through the use of a third enzyme process that causes the formation of fructose. This conversion is preferably accomplished using an immobilized glucose isomerase enzyme. Immobilized glucose isomerase refers to a preparation of microbially derived glucose isomerase enzyme absorbed on and within a granular and water-insoluble carrier such as silica gel or aluminum oxide. The particle size of the water-insoluble carrier is preferably approximately 30xc3x9750 US Standard mesh.
A typically preferred method of treating glucose syrup with immobilized glucose isomerase enzyme is by percolating the glucose syrup through a column or packed bed of immobilized glucose isomerase enzyme. However, the syrup product of the present invention contains significant levels of glucans, hemicelluloses, proteins, and lipids that tend to foul the column or packed bed. Because the glucans, hemicelluloses, proteins, and lipids play a important role in use of the syrup product as a non-dairy frozen confection, it is not possible to remove these components from the syrup product.
To overcome these limitations, the immobilized glucose isomerase enzyme is dispersed in the bulk phase of the syrup product. Introduction of the immobilized glucose isomerase enzyme into the syrup product is done after the initiation of the saccharification step. Preferably, the immobilized glucose isomerase enzyme is introduced into the intermediate syrup immediately following the addition of the saccharifying enzyme. This allows the saccharification of dextrins to form glucose and the subsequent conversion of part of the glucose to occur in the same time frame and at the same temperature. In this procedure, the intermediate syrup is preferably maintained at a temperature of between about 60xc2x0 C. and 65xc2x0 C. for between 3 and 4 hours.
A suitable proprietary immobilized glucose isomerase enzyme for use with the present invention is commercially available from UOP (Des Plaines, Ill.) under the name of KETOMAX(copyright) GI-101. Another suitable immobilized glucose isomerase enzyme for use in the present invention is available under the designation SWEETZYME(copyright) T from Novo Nordisk Biochem (Franklinton, N.C.)
The amount of the immobilized glucose isomerase enzyme used is selected upon the desired amount of additional sweetness in the syrup product. The concentration of the immobilized glucose isomerase enzyme is only limited by the practical rheological properties of the resultant mixture. High loads of enzyme carrier create difficulties with agitation of the mixture and lead to disintegration of the carrier due to abrasion between carrier particles. For most applications, the concentration of immobilized glucose isomerase enzyme is less than 20 percent by volume of the syrup. Preferably, the concentration of immobilized glucose isomerase enzyme is between about 0.5 and 2.0 percent by volume of the syrup.
Following the immobilized glucose isomerase treatment, the immobilized glucose isomerase enzyme is removed by screening. The mesh size of the screen is selected to effectively remove all of the immobilized glucose isomerase enzyme carrier. Selection of a separation method is based on minimizing damage to the glucose isomerase carrier. Methods that cause impact or abrasion damage to the carrier are less desirable due to contamination of the syrup product with fine particles of the carrier material.
A person of ordinary skill in the art will appreciate the various separation techniques, such as basket centrifuge, profile wire screens, filter presses, pressure strainers, and sedimentation vessels. A preferred method of removing the immobilize glucose isomerase enzyme from the syrup product is through a 120 mesh vibratory sifter.
After separation of the immobilized glucose isomerase carrier from the syrup product, the immobilized glucose isomerase enzyme may be reused with subsequent batches of syrup. Alternatively, the immobilized glucose isomerase enzyme is washed with potable water and stored for future use. To protect the enzyme carrier from bacterial deterioration during storage, a preservative is preferably applied to the enzyme carrier prior to storage.
Over time the glucose isomerase enzyme becomes denatured. The extent of enzyme degradation may be determined by tracking the rate of fructose conversion over several lots of syrup. When required, replacement material may be purchased as a single use material, or the exhausted carrier may be regenerated with fresh glucose isomerase enzyme, in a manner familiar to those skilled in the art.
After the syrup product obtains a desired degree of sweetness, the syrup product is cooled to a temperature of approximately 10xc2x0 C. The syrup product is clean and bland with no off-flavors.
The syrup product may be then flavored as desired using flavoring ingredients that are known in the art. For example, vanilla or cocoa may be added to the syrup product to produce vanilla or chocolate flavored non-dairy frozen confection. It may also be desirable to add a dairy- or cream-like flavor to the syrup product so that the non-dairy frozen confection tastes more similar to ice cream.
The flavor of the syrup product may be enhanced by the addition of a small concentration of a flavor enhancer. Various flavor enhancers are known in the art and are selected based upon the particular flavoring ingredients that are used in the non-dairy frozen confection. It is also possible to enhance the flavor of the non-dairy frozen confection by adding salt in a concentration of approximately 0.35 percent by weight of the syrup product. It is believed that adding salt to the syrup product after the syrup product is formed minimizes off-flavors resulting from the addition of the salt while the syrup product is being prepared.
After the syrup product is flavored, the syrup product is frozen to produce the non-dairy frozen confection. The freezing is accomplished using processes and machines that are conventionally used to produce soft-serve or hard-pack prior art frozen confections.
The non-dairy frozen confection of the present invention surprisingly exhibits desirable functional characteristics of a frozen confection but does not require the use of exogenous sweeteners, stabilizers, emulsifiers, or proteins to produce the desirable functional characteristics. For example, the sweetness of the non-dairy frozen confection results from the glucose and fructose produced during the saccharification and glucose isomerization steps.
The non-dairy frozen confection exhibits desirable viscosity characteristics without the addition of exogenous sweeteners, stabilizers, emulsifiers, or proteins. It is believed that the desirable viscosity characteristics result from the naturally occurring fiber and gums in the starch sources. In particular, the texture of the non-dairy frozen confection depends upon beta-glucan being naturally present at a level sufficient for beta-glucan to act both as a stabilizer and texturizing agent in the syrup product.
Additionally, the non-dairy frozen confection exhibits texture and mouthfeel that are similar to ice cream, frozen yogurt, and other similar frozen confections. It is believed that the naturally occurring fat, protein, and fiber in oats result in the non-dairy frozen confection exhibiting a smooth mouthfeel characteristic. Furthermore, the syrup product does not require emulsification or homogenization to produce the smooth mouthfeel characteristic in the non-dairy frozen confection of the present invention.
A person of ordinary skill in the art would appreciate that additives, such as pectin, gums, emulsifiers such as mono- and di-glycerides, bodying agents including cyclodextrose and maltodextrins, and the like, may be added to change the texture of frozen confections made primarily from oats. However, such additives are unnecessary for the production of a satisfactory soft-serve frozen confection, and would tend to lessen the consumer appeal of a product free of additives.
A person of ordinary skill in the art would also appreciate that the syrup product produced in the present invention could be used to formulate items other than frozen confections. For example, the syrup product may be used to produce shakes, malts, and puddings. The syrup product may also be incorporated into carbohydrate-loading beverages that take advantage of the same physical and nutritional characteristics that make the syrup product of the present invention useful for frozen confections.